Sinking or falling of foundations of building structures are a common problem. Resulting movements of the foundation can result in substantial structural damage to the building including cracks in walls, misalignment of doorjambs and window frames, and bulging walls among others. The sinking is generally a result of the underlying substrate having insufficient strength or stability to support the foundation. The substrate may be of a type or form that is inherently weak, such as silt, sands, or organic materials, or the substrate may be weakened as a result of natural occurrences like unusually high or low rainfall or freeze-thaw effects. Non-natural activities, such as nearby construction activities, digging, or blasting, among others might also weaken the substrate.
Typically, hydraulic lifts or jacks are employed to lift the foundation and insert a series of support posts or piers beneath the foundation. The piers are preferably driven through the substrate to contact an underlying stratum, e.g. bedrock that is of sufficient strength to support the foundation. The piers are commonly constructed of steel pipes, tubes, or beams or of concrete pre-forms. Or holes can be dug or augered beneath the foundation and concrete or similar materials poured or injected therein to form piers.
Available apparatus for lifting the foundation and installing the piers thereunder employ a bracket that is coupled to a bottom edge of the foundation or associated footing by a plurality of fasteners driven through the bracket and into the foundation. The bracket may provide a guide for driving the pier vertically downward generally parallel to a wall of the foundation and spaced a short distance outwardly away therefrom.
Known configurations create a large rotational force about the interface between the bracket and the foundation due to the lever arm formed by the spacing of the pier away from the foundation wall. The rotational force may tend to rotate or bend the bracket and may cause the pier to bend or bow under load. As a result, the bracket and the upper portion of the pier located above the bracket may rotate toward the wall of the foundation and create difficulties in operation of hydraulic units coupled thereto as well as for insertion of additional pier segments into the bracket during installation thereof.
A foundation-piering system that reduces the rotational forces encountered by the bracket is needed. A foundation-pier bracket that does not require attachment to the foundation would also be advantageous. And a foundation-piering system that provides an operating location for pier-driving apparatus that is spaced away from the foundation and that is easily adjustable after completion of a foundation leveling is needed.